Diffusers



Oct. 22, 1957 U DIFFUSERS Original Filed- July 31, 1947 DYD) INVENTORALFRED BUCHI- United States Patent DIFFUSERS Alfred Buchi, Hurden,Schwyz, Switzerland Original application July 31, 1947, Serial No.765,217,

now Patent No. 2,635,849, dated April 21, 1953. Divided and thisapplication January 23, 1953, Serial N 0. 332,980

Claims priority, application Switzerland August 13, 1946 2 Claims. (Cl.25340) This invention relates to improvements in diffusers generally,and specifically pertains to outlet diffusers for turbines driven by hotgases. The present application is a division of my application SerialNo. 765,217, filed July 31, 1947, now Patent No. 2,635,849, grantedApril 21, 1953.

The desirability of providing a diffuser downstream of the turbineblading to effect conversion of the gas velocity into pressure has beendiscussed in my prior U. S. Patent No. 2,486,732, and is further dealtwith in my said application Serial No. 765,217, now Patent No.2,635,849. However, since turbochargers of the type therein illustratedand described, when applied to internal combustion engines devoted, forexample, to traction, truck and marine purposes, do not operate underconstant conditions of exhaust gas pressures and temperatures, it is notpossible to design a fixed outlet diffuser for the turbines in suchunits to operate efliciently over the entire range of such conditions.The best that can be done with a fixed outlet dilfuser is to design itfor most efiicient conversion of velocity of the gases into pressure ata certain rather limited range which is usually selected upon the basisof the conditions under which maximum efliciency of the turbocharger ismost important.

It is an object of my present invention to enable the capacity of thediffuser to be varied so that conversion of velocity into pressure maybe carried out at peak efiiciency over a wider range of gas temperatureand pressure conditions.

It is also an object to enable a single size outlet diffuser to be madefor attachment on turbochargers employed in different types of engineinstallations.

It is also an object to devise a turbine arrangement in which such adiffuser is particularly useful.

These and other objects are accomplished by my novel variable diffuserand the turbine hereinafter described and illustrated in theaccompanying drawing representing an elevation, partly in section, of aturbocharger in conjunction with which my variable diffuser mayprofitably be employed.

In this figure, 1 designates the turbine wheel and 2, the bladingthereon. 3 is a guide casing provided with vanes 4. 5 is the turbineinlet casing defining a single duct 6. 5a is the gas receiving space ininlet casing 5. 9 represents a diffuser arranged adjacent the rotorwheel 2 and having inner and outer walls formed by cones 12 and 14respectively. The axis of symmetry of these cones will be seen to lie inthe turbine axis. 13 are support ribs.

The blower delivery is designated by 19, and represents the bearinghousing. 21 and 22 constitute slotting in the duct walls to supportguide vane 23. 24 and 25 are casing sections forming part of the turbineand blower housings.

My novel diffuser-11' is attached to follow the conical difiuser 9 andcomprises the conical outer wall 10, the flange 10a of which is securedto the flange 14a of outer wall 14, the coaxial rod 11", and the conicalfilling piece 11", slidable on said rod. The filling piece 11" has anapex and a rear end wall. By changing the location of this fillingpiece, the cross sectional area through which the gases flow may bevaried. By this means I succeed in altering the effect of ditfuser 11'and, as a result, I can achieve the most favorable transition ofvelocity into pressure, depending on the quantity of gases flowingthrough the turbine under different operating conditions of the internalcombustion engine. Such a feature is particularly important in the rangeof higher velocities of pressure gases.

While I have illustrated and described my present invention as appliedto an exhaust gas turbocharger, many applications of the principle heretaught will readily occur to any person skilled in the art, and thescope of my protection should not be. limited to variable diflfusers inturbochargers.

I claim:

1. In combination with an exhaust gas turbine, said turbine comprisingguide means for directing the actuating medium through the blading in adirection having a diagonal axial direction and having an inner guideWall consisting of the outer surface of a conical body, said body beingcoaxial with the rotor, having the periphery of its base substantiallyfairing with the bases of the rotor blading, and its apex axially spacedfrom said rotor, and an outer guide wall defined by the inner surface ofa frustrum of a hollow conical body defining a conical space coaxialwith said rotor, having the periphery of its base substantially fairingwith the outer edges of the rotor blades, said latter wall being flaredout in axial direction from the rotor blading relative to andoverlapping the surface of said conical body thereby forming a passageadapted to continue the actuating medium in approximately the samediagonal axial direction as the direction of entry to the rotor blading,and a variable difiuser secured to the end of said inner guide wall,said diffuser comprising a peripheral wall on the axis of the rotorflaring out towards the outside symmetrical to said axis, a rod locatedin said hollow conical body coaxial with said rotor, a conical fillerpiece slidably mounted on said rod, the conical outer surface of saidfiller piece flaring out towards the outside on the axis of said rotoras symmetry axis, said filler piece comprising an apex coaxial with saidrotor and said conical body and directed towards the latter, and a rearend wall, the end of said filler apex being axially spaced from saidrear end wall at a distance substantially equal to the axial length ofsaid conical space, and being slidably disposed on said rod for axialdisplacements in either direction, whereby said filler apex may be movedto various positions in said conical space forming thereby increasing ordecreasing through flow areas Within said conical space, contingent onthe direction of displacement of said coni cal filler, whereby suchthrough flow areas are changed to provide optimum conditions forconversion of the velocity of the actuating gas quantity into pressure.

2. A hot gas turbine comprising an axially directed dilfuser, a rotorfrom which the actuating medium flows out over said axially directeddiffuser, a cone converging from the rotor blading toward the turbineaxis, said cone extending beyond the rotor blading and into the entranceconical filling :piecemounted --beh nd-saidcone=- diverging outwardly inthe axial direction and extending at least approximately as far as theend of said diffuser, and means for the adjustment of said displaceablefilling piece, said means being adapted to move the filling piece fromsubstantially within the diffuser to the outside thereof, whereby thethrough fiow areas in said difiuser provide optimum conditions forconversion of the velocity of the actuating me mn antityr nto PI 581 1UNITED STATES PATENTS Taylor Mar. 5, 1929 Moody Dec. 23, 1930 HeintzeAug. 21, 1945 FOREIGN PATENTS Norway Apr. 27, 1925

